An alteration of the taste and smell of seafood is one of the phenomena
which can often be observed after an oil
spill. Simple contact of hydrocarbons
present in the water with the skin or gills can give marine animals a taste
and smell considered unacceptable by consumers. Such a taste, sometimes
clearly perceived as an “oil-like” taste, sometimes simply recognised
as different from the usual taste, is known as tainting.

This particular effect is a serious issue in the management of the consequences
of an oil spill. Molluscs, such as oysters and mussels, can absorb, through
filtering, considerable quantities of hydrocarbons present in water. For
example, a 20 gramme oyster filters some 48 litres of seawater per day.
It can multiply the concentration of a pollutant in its tissues by 70,000
in relation to the surrounding environment.

Sea bass in an experimentation tank

Tainting can occur very quickly. It only takes a few hours to a few days of
contact for the taste and smell to alter. Tainting can be tested through
olfactory or organoleptic tests and can be quantified by analyses of the
total hydrocarbon content in the organism’s tissues. When transferred
into hydrocarbon-free water, or when the pollution has ceased, the animals
naturally purge themselves of the pollutant in a few weeks to a few months.

The tainting of crustaceans, fish and shellfish is common during an oil
spill. The immediate response from authorities is to temporarily ban their
collection or sale. It must then be determined whether the contaminated
animals can be put on the market after decontamination or if they should
be destroyed as a precaution. This question is an important issue in terms
of the protection of consumers and the local economy, as well as the market
reputation of the local seafood industry.